Crocheting all those circles was a little more tedious and time consuming at first than I had anticipated, but once I got into a rhythm things sped up and went pretty quickly.
I did discover that you've got to make sure all your jump rings are closed super tight! Otherwise the thin embroidery thread will manage to slip out and you'll be dripping circles everywhere. Trust me. Learned this one the hard way. Next time I think I might try split rings rather than jump rings.
I am in love with the end result! And already picturing it made in shades of black/white/gray, blues, or a rainbow of colors!
If you love it too, you can find the tutorial at: http://www.happytogethercreates.com/2011/05/color-my-summer-circles-of-green.html